Sheet feeder with a light sensor

ABSTRACT

A sheet feeder includes a housing, a cover and a sensing device. The cover is mounted on the housing, and the sensing device is disposed between the housing and the cover. The sensing device includes a light sensor and a reflecting mirror. The light sensor is mounted on the inside surface of the cover, and the reflecting mirror is mounted on the housing opposite the light sensor. As a signal light is being emitted from the light-emitting unit of the light sensor, the signal light is reflected from the reflecting mirror or a document and received by the receiving unit of the light sensor. The reflected signal light will then be transformed to a signal voltage which, according to its value, indicates the using status of the sheet feeder, such as ‘without document’, ‘document present’ or ‘cover open’, such that the number of the sensors on the sheet feeder can be reduced and the manufacturing costs can be lessened.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a sheet feeder structure. Thesheet feeder is mounted on a scanning device to provide an automaticdocument feeding function. More particularly, the sheet feeder comprisesa housing and a cover and the housing is functioning in conjunction withthe cover, and a sensing device is disposed between the cover and thehousing. The intensity of the signal light emitted and received by thesensing device indicates the operational status of the sheet feeder,namely, whether or not a document is present or whether the cover isopen or closed.

2. Description of the Prior Art

The scanning device is used to scan images. The scanning is executed viathe relative motion of an optical mechanism mounted in the scanningdevice and a to-be-scanned document. A sheet feeder is usually used tofeed to-be-scanned documents the relative motion.

As shown in FIG. 1, a sheet-feeding scanner 10 is combined with a sheetfeeder 12, such that the optical mechanism (not shown in the figure) inthe sheet feeder 12 is capable of scanning images when to-be-scanneddocuments are fed in.

As shown in FIG. 2, a flatbed scanner 20 is combined with a sheet feeder22. The sheet feeder 22 is capable of feeding to-be-scanned documents bythe optical mechanism in the scanner 20.

FIG. 3 is a schematic view showing the structure of a sheet feeder 30,which is similar to the structure of the two aforementioned sheetfeeders. The sheet feeder 30 has a housing 32 and a cover 34. Thehousing 32 has an internal combination structure comprising a pluralityof rollers and transmission belts (or gears). Automatic pickup andfeeding of to-be-scanned documents are executed via the rollercombination. The cover 34 is joined with the housing 32 pivotally andcan be opened or closed against the housing 32.

In a typical sheet feeder, a cover sensor 36 is disposed between thecover 34 and the housing 32 to detect whether the cover 34 is open. Whenthe cover 34 is open, the automatic document feeding function of thesheet feeder 30 is suspended. A light sensor 38 is also disposed betweenthe cover 34 and the housing 32 to detect whether there is anyto-be-scanned document in the feeding passage of the sheet feeder 30. Ifno document is in the feeding passage, the automatic document feedingfunction is suspended.

In addition to the sensor to detect the open/closed status of the cover34, a sheet feeder 30 with the aforementioned structure requires anotherindependent sensor to detect whether any to-be-scanned document is inthe feeding passage. Any additional structures would increase the numberof parts used, which in turn would increase the cost of the production.

SUMMARY OF THE INVENTION

The present invention provides a structure of a sheet feeder which has asensor and a reflecting mirror mounted between the housing and the coverof the sheet feeder. The sensor detects the open/closed status of thecover and detects the presence of a document in the feeding passage viathe interaction of the sensor and reflecting mirror.

More particularly, a light sensor is mounted on the inside surface ofthe cover and a reflecting mirror is mounted on the housing opposite tothe light sensor and forms a non-parallel configuration with the lightsensor. Through this non-parallel configuration, the open/closed statusof the cover is readily detected. A signal light is emitted by alight-emitting unit of the light sensor, reflected by the reflectingmirror and at last received by a receiving unit of the light sensor. Thesignal light received by the light sensor is then transformed todifferent signal voltage values, which would, in result, indicate thedifferent operational statuses of the sheet feeder.

The following is a preferred embodiment of the present inventiondescribed based on the objective, functional and structuralconfiguration thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a sheet-feeding scanner;

FIG. 2 is a perspective view of a combined set of a flatbed scanner anda sheet feeder;

FIG. 3 is a schematic view showing a structure of a prior art sheetfeeder;

FIG. 4 is a schematic view showing the structure of the presentinvention;

FIG. 5 is a schematic view showing the using status without documents tobe scanned;

FIG. 6 is a schematic view showing the using status with documents to bescanned;

FIG. 7 is a schematic view showing that the cover of the presentinvention is opened; and

FIG. 8 is a schematic view showing the structure of another embodimentof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 4 is a schematic view showing the structure of a sheet feeder 40.The sheet feeder 40 is capable of working together with a sheet-feedingscanner or a flatbed scanner. The sheet feeder 40 has a plurality ofrollers and transmission devices inside (not shown in the figure).

The sheet feeder 40 includes a housing 42 and a cover 44, and most ofthe aforementioned rollers and transmission devices are mounted in thehousing 42. The cover 44 is joined with the housing 42 pivotally and canbe opened or closed against the housing 42.

A sensing device 50 is mounted between the cover 44 and the housing 42.The sensing device 50 includes a light sensor 52 and a reflecting mirror54. The light sensor could be, for example, an infrared sensor, a LEDsensor and etc. The light sensor 52 has a light-emitting unit 522 and areceiving unit 524, which are mounted on the inside surface of the cover44 and can be positioned side by side.

The reflecting mirror 54 is mounted on the housing 42 opposite the lightsensor 52. The reflecting mirror 54 is finely adjusted such that thereflecting mirror 54 forms an angle in a non-parallel position oppositethe light sensor 52.

FIG. 5 shows that there is no to-be-scanned document in the feedingpassage between the cover 44 and the housing 42. A signal light isemitted from the light-emitting unit 522 and reflected from thereflecting mirror 54, and then received by the receiving unit 524. Sincethe reflecting mirror 54 has a high reflectivity, the receiving unit 524receives a reflected signal light of a high intensity. The receivedsignal light intensity is then transformed to a signal voltage of a highvoltage value V1.

FIG. 6 shows that there is a to-be-scanned document 62 in the feedingpassage 60. A signal light is emitted from the light-emitting unit 522,reflected from the to-be-scanned document 62, and then received by thereceiving unit 524. Since the signal light is reflected by theto-be-scanned document 62, which has a lower reflectivity than that ofthe reflecting mirror, the receiving unit 524 receives a signal light ofa lower intensity. The received signal light intensity is thentransformed to a signal voltage of a lower voltage value V2, and V2<V1.

FIG. 7 shows that the cover 44 is open. Only a part of the signal lightemitted by the light-emitting unit is reflected from the reflectingmirror 54 and, in turn, received by the receiving unit 524. The receivedsignal light is then transformed to a signal voltage with a value of V3,and V3<V2.

The design concept as described in the aforementioned embodiment is toutilize the changes in the intensities of the signal light received bythe receiving unit 524 as the document 62 is fed to the sheet feeder, nodocument 62 is fed and the cover 44 is open, and to determine theoperational status of the sheet feeder according to the differentvoltage values transformed from the different intensities of thereflected signal light. For example, V1 greater than 3V indicates thatthere is no to-be-scanned document 62 and the cover 44 is closed. V2between 1.7V and 1.8V indicates that there is a to-be-scanned document62 entering the feeding passage 60. V3 less than 1V indicate that thecover 44 is open. The present invention needs only one sensing deviceand can reduce the production cost effectively in comparison withexisting state of art, which need two sensing devices.

In the aforementioned embodiment, the light sensor 52 is mounted on theinside surface of the cover 44, while the reflecting mirror 54 ismounted on the housing 42. FIG. 8 shows another embodiment in which thereflecting 54 is mounted on the inside surface of the cover 44, whilethe light sensor 52 is mounted on the housing 42. The reflecting mirror54 and the light sensor 52 are positioned opposite each other and form anon-parallel configuration. This embodiment is carried out in the sameway as the previous embodiment.

Although the present invention has been disclosed and illustrated withreference to the preferred embodiments, the principles involved can beapplied for use in numerous other embodiments that will be apparent topersons skilled in the art. The present invention is, therefore, to belimited only as indicated by the scope of the appended claims.

1. A sheet feeder with a light sensor to be mounted on an image scanningdevice which provides an automatic feeding function for a to-be-scanneddocument comprises: A housing; A cover mounted on said housing andopened or closed against said housing; A feeding passage formed betweensaid cover and housing for the to-be-scanned document; A sensing devicemounted between said housing and cover; Said sensing device comprising alight sensor and a reflecting mirror opposite to said light sensor; saidlight sensor receiving signal lights of different intensities underdifferent circumstances, such as when no said to-be-scanned document isfed, when said to-be-scanned document is fed, and when said cover isopen; said signal lights of the different intensities being thentransformed to different voltage values and said voltage value servingas an indication of the operational status of said sheet feeder.
 2. Thesheet feeder of claim 1, wherein said light sensor of said sensingdevice and said reflecting mirror are opposite to each other and form anon-parallel configuration.
 3. The sheet feeder of claim 1, wherein saidlight sensor has a light-emitting unit and a receiving unit.
 4. Thesheet feeder of claim 3, wherein said light-emitting unit and saidreceiving unit are mounted on an inside surface of said cover.
 5. Thesheet feeder of claim 3, wherein said light-emitting unit and saidreceiving unit are mounted on said housing.
 6. The sheet feeder of claim1, wherein said image scanning device is a sheet-feeding scanner.
 7. Thesheet feeder of claim 1, wherein said image scanning device is a flatbedscanner.
 8. The sheet feeder of claim 1, wherein the voltage value isdefined as V1 when no said to-be-scanned document is fed, the voltagevalue is defined as V2 when said to-be-scanned document is fed, and thevoltage value is defined as V3 when said cover is open, and V1>V2>V3.